Blood sampling devices

ABSTRACT

A blood sampling device includes a housing and a lancet supporting a lancet needle or tip, the lancet and needle being urged or urgeable in a pricking direction. A trigger mechanism is moveable to a fire position for releasing the lancet to travel in the pricking direction. A removable safety cap initially covers the lancet needle. The lancet has an initial position in which movement of the trigger mechanism to its fire position is blocked and an intermediate position in which the trigger mechanism may be moved to its fire position. The intermediate position is obtainable only on removal of the safety cap.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to blood sampling devices of the type whichemploys a sharp tip or needle to obtain a small sample of blood fortesting purposes.

Description of the Related Art

Known blood sampling devices employ a spring or the like which forces aneedle tip into the skin following triggering of the device. Embodimentsof this invention are concerned with improving the safety of suchdevices to reduce the risk of accidental triggering where a manuallyactuated trigger is employed. In addition it is known from eg our ownearlier WO2005/013825 to provide a needle cap which is removable priorto use of the device. However, in some instances, if a user does notfollow the written and visual instructions to twist the cap off they mayforce the cap off in a way that causes the device to malfunction.

WO2007/050528 discloses a single use lancing device having a removablecap that prevents the lancet from being moved to a puncture positionbefore the cap is removed. After removal of the cap the device is firedby depressing a firing button which pushes the lancet forward to forceprotrusions on the lancet past cantilevered heads on the housingthereafter to be driven forwards.

BRIEF SUMMARY OF THE INVENTION

According to one aspect, the invention provides a blood sampling devicecomprising:

a housing;

a lancet body having associated therewith a sharp tip, the lancet bodybeing urged or urgeable forwardly in a pricking direction;

a trigger mechanism moveable to a fire position for releasing the lancetbody to travel in the pricking direction; and

a removable safety cap for at least partially covering the lancet tip;wherein the lancet has an initial position in which movement of thetrigger mechanism to its fire position is blocked and an intermediateposition in which the trigger mechanism may be moved to its fireposition, said intermediate position being obtainable upon removal ofthe safety cap.

Thus, the device cannot be triggered until the cap is removed, and thisreduces the risk of accidentally activating the trigger mechanism priorto removal of the cap.

The firing mechanism may take many forms; it may comprise a manuallyoperable firing button or the like. This is conveniently located on theside of the device so that the device is fired by applying pressure in adirection transverse to the pressure direction but other orientationsare possible such as on the rear of the device.

Preferably the trigger mechanism comprises a trigger member movable froma rest position, in which it restrains movement of said lancet body, tosaid fire position in which said restraint is removed. Preferably saidtrigger member is mounted to move generally transversely to the forwardpath of the movement of the lancet body. Preferably said trigger memberis mounted for rocking movement relating to said housing. The rockingmovement may be about an axis transverse to the forward path of themovement of the lancet body.

In an embodiment, the cap is removable in the pricking direction andwhen removed allows the lancet body to be urged in the prickingdirection by a spring into the intermediate position ready for furtherurging by the spring when the trigger mechanism is operated to releasethe lancet body for forward movement from the intermediate position.

In an embodiment, the lancet includes an abutment surface engageable inblocking alignment with an abutment surface of the trigger mechanism toprevent movement of the trigger mechanism into the fire position whenthe lancet is in said initial position.

Conveniently, the abutment surface on the lancet is moveable with thelancet to the intermediate position when the cap is removed, whereuponthe respective abutment surfaces are no longer in blocking alignment,and thereby movement of the trigger mechanism into its fire position ispossible.

Preferably the intermediate position is maintained by the engagement ofa pawl of the trigger mechanism with a latch surface of the lancet. Thelancet body may support a lancet needle which provides said sharp tip orthe tip may be integrally formed therewith.

Conveniently the trigger mechanism includes a tiltable trigger leverhaving a hinge region between the trigger abutment surface and the pawl,and said engagement of the trigger abutment surface and the lancetabutment surface prevents or limits hingeing of the trigger lever.

Preferably, the spring is in the form of a compression spring which actson the housing and the lancet to provide said urging.

Conveniently, the cap has a graspable portion external to the housingand a stem substantially within the housing.

Preferably, said stem includes one or more projections which extend in aplane perpendicular and/or transversely to the pricking direction, andthe housing includes a complementarily shaped aperture, the cap beingcaptured by the stem projections in the aperture, but being releasablefrom said aperture upon twisting said cap to cause the or eachprojection and the complementarily shaped aperture to be in substantialalignment.

In an embodiment the projections include a pair of opposed barbs oneither side of the stem and the aperture is in the form of a slot whichallows the forward passage of the barbs in one orientation of the barbsbut prevents their forward passage in other orientations.

According to another aspect the invention provides a blood samplingdevice comprising:

a housing having an aperture in a forward end thereof:

a lancet body with an associated sharp tip located within said housing;

a cap having a stem portion which covers the needle and extendsforwardly through said aperture to merge with an externally accessibletab portion;

a locking arrangement for restraining forward movement of said cap andbeing twistably releaseable from a locked position to a releasedposition,

wherein said locking arrangement comprises respective abutments on saidstem portion and said housing, which are aligned to block forwardmovement of the cap when it is in the locked position but which allowforward movement from a pre-firing to an armed position when the cap istwisted to its free position, and at least one of the locking abutmentsis resiliently moveable to allow it to be snapped rearwardly past thecooperating abutment during assembly.

In this manner the abutments may be disposed within the housing andinaccessible from outside thereby reducing the opportunity for forciblerelease.

Conveniently said locking abutment on said housing comprises a wall ofan aperture through which the stem may pass on release. The slot may bea transverse slot of elongate form, and the locking abutment on saidstem conveniently comprises two oppositely directed transverseprojections from said stem. Advantageously the stem is provided with tworesiliently moveable abutments. Conveniently the or each abutment is ofbarbed form, and ideally integrally formed on a slotted portion of saidstem, thereby to provide resilience.

According to another aspect, this invention provides a method ofproducing a blood sampling device which includes:

providing a housing having an aperture in a forward end thereof andmoveable from an open position to a closed position during assembly,

providing a lancet body having an associated sharp tip and including anintegrally formed cap comprising a stem which at least partially coversthe tip and extends forwardly to merge with an externally accessibletab, the stem having at least one abutment that cooperates in use withan abutment on the housing,

locating the lancet body with its integrally formed cap and the devicespring in the housing when open, with the spring in a relatively relaxedstate and the tab spaced forwardly of the housing,

closing the housing, and

thereafter effecting relative movement of the cap rearwardly withrespect to the housing to compress the drive spring and to snap the theor each abutment past the abutment in the housing to retain the lancetin a firing or pre-firing position by engagement of said abutments.

In yet another aspect this invention provides a blood sampling devicecomprising:

a housing;

a lancet body having a sharp tip and being urged or urgeable forwardlyin a pricking direction, and

a manually operable trigger member movable to a fire position forreleasing the lancet to travel in the pricking direction,

wherein the lancet has:

-   -   an initial position in which movement of the trigger member to        its fire position is blocked by an abutment surface on the        lancet body being in blocking alignment with a complementary        abutment surface on said trigger member, and    -   an intermediate position spaced forwardly of the initial        position in which the abutment surfaces are shifted out of        alignment so that the trigger mechanism may be moved to its fire        position.

The invention extends to any single feature or combination of thefeatures mentioned herein or illustrated in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be put into effect in various ways, and one embodimentwill now be described below, by way of example only, with reference tothe drawings wherein:

FIG. 1 shows a longitudinal section through a blood sampling device;

FIG. 2 shows the section shown in FIG. 1, as a perspective view;

FIG. 3 is a perspective view similar to FIG. 2, with the cap twistedthrough 90° and the lancet shifted forwardly into engagement with thetrigger;

FIG. 4 shows an enlarged sectional partial view of the device shown inFIG. 1 showing the cap attachment;

FIG. 5 shows the integral cap and lancet 8 of the device shown in FIG.1; and

FIG. 6 is a view of one end of the device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, the main components of the blood samplingdevice 10 are a housing 20, a lancet 30 movable within the housing 20,and a coil spring 40 for causing pricking movement. The housing 20includes a trigger mechanism 22, and the lancet includes an integrallymoulded safety cap 32 which covers a lancet needle 36. The cap 32comprises an externally accessible tab connected to the remainder of thelancet 30 by means of a stem 33 which has a frangible connection 34 atthe interface with the lancet.

The housing 20 is formed from moulded plastics in two hinged halves.During assembly, the lancet 30 and spring 40 are located substantiallywithin the two halves of the housing 20 in the arrangement shown in FIG.1, with the spring 40 in its relaxed position. To complete the assembly,the safety cap is pushed back into the housing where it latches therebycompressing the spring 40 and so urging the lancet 30 in a prickingdirection shown by arrow P. The lancet 30 is prevented from moving inthe housing 20 because the safety cap 32 interlocks with an end face 38of the housing 20 and restrains the lancet 30 from movement. This is theinitial, as assembled, condition of the device 10 with the lancet heldin a pre-firing position, back from an armed position.

The trigger mechanism 22 includes a push button 24 which hinges abouttwo transverse live hinges 21 that connect it to the housing. The buttonhas a lower rib 26 which is engageable with a boss 35 formed on thelancet 30. In the initial position shown, the boss prevents depressionof the trigger button 24 and so prevents operation of the triggermechanism.

The safety cap 32 has a graspable tab 31 which in use is held andtwisted by 90° in the direction of arrow S, i.e. about the direction ofpricking, in order to remove it (FIG. 3). The cap 32 is then freeablefrom the housing 20 in a manner described below. The twisting actionbreaks the frangible connection 34 and withdrawal of the cap 32 in thedirection of arrow P exposes the skin pricking needle 36 inside thehousing 20. Thus, until this time the needle is hermetically sealedprior to use.

The removal of the cap 32 also simultaneously allows the lancet 30 tomove forward in the direction of arrow P, into an intermediate positionin which a detent 37 on the lancet 30 abuts a pawl 28 of the triggermechanism 22. In this position, the push button 24 is no longerprevented from being depressed because the boss 35 has moved forward outof the path of the rib 26. Thus the device is armed and ready for useonce the cap has been fully withdrawn in the direction of arrow P.

Once the cap 32 has been removed, the device is ready to be fired, byholding the proximal end against the skin, and depressing the triggerbutton 24. That action lifts the pawl 28 about the live hinges 21. Inturn the detent 37 is set free and the spring 40 forces the lancet 30 inthe direction of arrow P, so that the needle 36 protrudes from theproximal end of the housing 20, to puncture the skin, and thereafterrebound so that the tip is returned safely within the housing but withthe lancet well forward of the cocked position.

FIG. 4 shows an enlarged view of the proximal end of the device with onehalf of the housing removed for clarity. The lancet 30, as mentionedabove, includes a removable safety cap 32 which is initially held inplace by an interlocking arrangement with the housing. Two sprung barbs39 are formed on the stem 33 of the cap 32 and abut the end 38 of thehousing 20 to prevent movement of the cap under the influence of spring40. The barbs 39 are sprung by provision of a slot 41. When the cap 32is twisted through 90 degrees, the frangible connection 34 connectingthe valve 33 of the cap 32 to the lancet 30 is broken, and the barbs 39align with a complementary slot 29 (FIG. 6) in the housing 20 and thecap is pushed partially out of the housing by the drive spring until thelancet reaches the intermediate position mentioned above. Thereafter thestem 33 of the cap 32 can be pulled out of the housing 20 via theaperture 29.

The profile of the barbs 39, the resilience afforded by the slot 41, andthe dimensions of the slot 29 are selected so that during assembly,having located the integrally formed lancet 30 and cap 32 in the housingtogether with the spring 40 in a relaxed extended condition, theassembly may be completed by pushing the cap into the body until thebarbs 39 snap past the slot 29 thereby cocking the spring 40, andlocking the cap and lancet in the initial position against forwardmovement until the cap is released by twisting.

FIG. 5 shows the integral plastics moulding of the lancet 30 and the cap32. The frangible connection 34 connecting the cap 32 to the remainderof the lancet 30 is visible.

FIG. 6 shows the slot 29 which allows the cap to escape once it istwisted, and when the barbs 39 and slot 29 are in alignment.

The invention claimed is:
 1. A blood sampling device, comprising: ahousing (20) having an aperture (29) in a forward end thereof; a lancetbody (30) with an associated sharp tip (36) located within said housing;a cap (32) having a stem portion (33) which at least partially coversthe sharp tip (36) and extends forwardly through the aperture (29) tomerge with an externally accessible tab portion (31); and a lockingarrangement (39, 29) for restraining forward movement of said cap (32)and being twistably releaseable from a locked position to a releasedposition, wherein said locking arrangement comprises respectiveabutments (39) on said stem portion (33) and said housing, which arealigned to block forward movement of the cap (32) when the cap is in alocked position and which allow forward movement from a pre-firing to anarmed position when the cap is twisted to from the locked position to afree position, and at least one of the abutments (39) is resilientlymovable to allow said at least one of the abutments (39) to be snappedrearwardly past a cooperating abutment during assembly, wherein eachabutment (39) on the stem portion (33) is resiliently moveable, andwherein said abutments are integrally formed on a slotted region of saidstem portion (33), thereby to provide resilience.
 2. The blood samplingdevice according to claim 1, wherein said abutment on said housingcomprises a wall of said aperture (29) through which the stem portion(33) may pass on release.
 3. The blood sampling device according toclaim 2, wherein said aperture (29) is a transverse slot of elongateform, and the abutment on said stem portion comprises oppositelydirected transverse projections (39) from said stem portion (33).
 4. Theblood sampling device according to claim 1, wherein each abutment (39)is of barbed form.